Choosing the Right Orchid for Your Climate

For many South Australian orchid growers, a shade house is the ideal environment. It allows orchids to benefit from natural light and air movement while providing protection from Adelaide's intense summer sun.

The amount of shade required varies with the season and the type of orchid being grown. Additional shade may be necessary during summer, particularly on very hot days, while greater light levels can generally be allowed during the cooler months.

A well-designed shade house should provide:

• Protection from direct summer sun
• Good ventilation and air movement
• Protection from hot, drying northerly winds
• Appropriate shading for the orchids being grown
• Good drainage and easy access for watering
• Some protection from winter cold, heavy rain and extreme weather

Genera such as Cymbidium, Cattleya, Australian Dendrobium, Sarcochilus and many Oncidium-alliance orchids can be successfully grown in protected outdoor or shade-house conditions in South Australia. However, each group has its own particular requirements.

Cattleyas are particularly rewarding shade-house orchids. They generally appreciate bright filtered light, excellent air movement and good drainage.

During Adelaide's hot summers they require protection from strong direct afternoon sun, while in winter they benefit from a bright position and some protection from prolonged cold and wet conditions. Many Cattleya hybrids are relatively robust and, with the right position, can be an excellent choice for South Australian growers.

Oncidiums are popular for their spectacular sprays of flowers, often carrying many individual blooms. However, the Oncidium alliance is a diverse group, and different types can require somewhat different growing conditions.

In South Australia, many commonly grown Oncidium hybrids perform well in a protected shade house with good air movement, moderate filtered light and regular watering during active growth.

Special attention should be given to summer heat and moisture. Adelaide's hot, dry weather can cause plants and potting media to dry very quickly. Oncidiums generally prefer not to remain completely dry for extended periods while actively growing. At the same time, their roots require good drainage and should never remain permanently waterlogged.

During periods of extreme summer heat, additional shading, more frequent watering and increased humidity around the plants may be beneficial. In winter, watering can usually be reduced, particularly when growth slows. More warmth-sensitive Oncidium-alliance orchids may also require additional protection from cold nights.

Because the group is so diverse, it is always advisable to check the requirements of the particular species or hybrid rather than assuming that all Oncidiums should be grown in exactly the same way.

Some warmer-growing orchids are better suited to the home, greenhouse or another protected environment. Phalaenopsis, for example, makes an excellent indoor orchid when provided with bright filtered light, suitable temperatures and careful watering.

Many tropical orchids will struggle if exposed directly to Adelaide's cold winter nights or prolonged summer heat. Understanding whether an orchid is naturally a cool-, intermediate- or warm-growing plant can therefore be more useful than simply choosing it for the appearance of its flowers.